1. Field of the Invention
The present invention relates to a radio knife (diathermic cutter) for resecting a living tissue by high-frequency incision.
2. Description of the Related Art
Conventionally, a living tissue, such as a mucous membrane, is resected by means of a surgical instrument that is inserted into a patient's body through a channel of an endoscope after the endoscope has been inserted into the body. A high-frequency surgical instrument, such as the one described in Jpn. Pat. Appln. KOKAI Publication No. 4-329944 (Patent Document 1), is used for the resection.
The high-frequency surgical instrument described in Patent Document 1 has an elongated insertion section and a control section on the manipulation side. The insertion section is inserted into a patient's body through a channel of an endoscope. The control section is coupled to the proximal end portion of the insertion section. The insertion section has a flexible tube and an operating wire. The operating wire is inserted into the flexible tube for axial movement. A needle-shaped knife element (electrode portion) that extends in the axial direction is provided on the distal end portion of the operating wire. The control section is provided with an operating handle. The operating wire is moved in the axial direction by manipulating the handle. A high-frequency current can be supplied to the knife element.
As the operating handle is manipulated, the operating wire is moved in the axial direction. The operating wire serves to move the knife element from a storage position to an operating position. In the storage position, the knife element is confined to the flexible tube. In the operating position, the knife element projects from the flexible tube. If a high-frequency current is supplied to the knife element in the operating position outside the flexible tube, the knife element cauterizes and incises a living tissue that it touches.
Further, the high-frequency surgical instrument described in Patent Document 1 is provided with liquid feed means that is used to feed a liquid, such as a drug solution, to the proximal end portion of the insertion section. The drug solution or the like can be supplied from the liquid feed means to the distal end side of the flexible tube through its bore and discharged through a distal opening of the tube.
As a publicly-known non-patent document, there is Non-patent Document 1: Tuneo Oyama, et al., “Extended Adaptation of Stomach EMR: Contrivance and Results of Method Aimed at Large En-block Resection; Endoscopic Mucosal Resection Using a Hooking Knife”, Stomach and Intestine, August 2002, Vol. 37, No. 9, pp. 1155-1161. The Non-patent Document 1 discloses a high-frequency treatment instrument having a structure different from that disclosed in Patent Document 1. The high-frequency treatment instrument has a bent portion made by bending a distal end of its needle-shaped knife section (electrode section). In use of the high-frequency treatment instrument, a living tissue is hooked onto the bent portion of the knife section, and cauterized and incised while being pulled up by the bent portion.
As another publicly-known non-patent document, there is Non-patent Document 2: Haruhiro Inoue et al., “Endoscopic Mucosal Resection with a Cap-fitted Panendoscope for Stomach Cancer”, Endoscopia Digestiva, A to Z for How to Select Endoscopic Treatment Tools, September 2002, Vol. 14, No. 9, pp. 1301-1302. The Non-patent Document 2 discloses a high-frequency treatment instrument having another structure. The high-frequency treatment instrument has a disc-shaped electrode portion at a distal end of a needle-shaped knife section (electrode section). In use of the high-frequency treatment instrument, a living tissue is hooked onto the disk-shaped electrode portion of the knife section, and cauterized and incised while being pulled up by the disk-shaped electrode portion.
If the living tissue is incised with use of either of these high-frequency surgical instruments, an incised region sometimes may bleed in the course of the incision. In this case, each instrument carries out the following processes of treatment. First, in the case of the high-frequency surgical instrument described in Patent Document 1, the working instrument is temporarily taken out of the channel of the endoscope. Thereafter, another surgical instrument for blood stanching is inserted into the channel of the endoscope, and hemostatic treatment is carried out. When bleeding has stopped, the high-frequency instrument of Patent Document 1 is inserted again into the channel of the endoscope, and the treatment is continued.
In the cases of the high-frequency surgical instruments described in Non-patent Literature 1 and 2, the bent portion on the distal end of the knife element or the distal end face of the disc is pressed against a bleeding point to supply high-frequency current to it. Thus, blood from the bleeding point can be coagulated so that bleeding is stopped.